Re: [Getfem-users] How to impose the normal derivative to zero on a model ?

[sébastien janas]

Thanks a lot,

So, the best is to use the function

add_normal_source_term_brick

on my boundaries with data a vector [ 0,0,0 ] ?

something like this

md.add_initialized_fem_data('WALL', mf, np.repeat([0,0,0],nbdof))
md.add_normal_source_term_brick(mim,'P','WALL',10)

10 is the tag of the boundaries.

Sorry to disturb you for such trivial things ;-)

Best regards,

Sébastien



Le jeudi 08 avril 2010 à 09:46 +0200, Yves Renard a écrit :
> Dear Sebastien,
> 
> No of course. For an order two isotropic pde, a homogeneous Neumann condition 
> reads as
> dU/dN = 0
> This condition does not add any term to the weak formulation. So you do not 
> have to add anything to the model.
> 
> Yves.
> 
> On mercredi 7 avril 2010, sébastien janas wrote:
> > Dear Yves,
> >
> > When we prescribe a zero neumann condition, we impose that the product
> > between the unknown and the normal vector is equal to zero, is it equal
> > to assume that the product bewteen the GRADIENT of the unknown and the
> > normal vector is equal to zero ?
> >
> > In other words, you advise me to do
> >
> > n x U = 0
> >
> > and I want to do
> >
> > dU/dn = 0
> >
> > is it equal ?
> >
> > Best regards,
> >
> > Sébastien
> >
> > Le mercredi 07 avril 2010 à 21:12 +0200, Renard Yves a écrit :
> > > Dear Sebastien,
> > >
> > > If you have to prescribe a zero Neumann condition to your unknown
> > > (assuming that it is an order two isotropic pde), you
> > > do not have to add anything to your model. This is somehow a default
> > > boundary condition as it add nothing to the weak formulation.
> > >
> > > Yves.
> > >
> > > sébastien janas <address@hidden> a écrit :
> > > > hi,
> > > >
> > > > I am using the python interface of getfem. I want to impose the normal
> > > > derivative of my unknow to zero at the boundary, but it seems that the
> > > > model method "add.normal_derivative_source_term" don't exist, is it
> > > > correct ? If yes, what's the best way to impose such a condition on a
> > > > model ?
> > > >
> > > > Thanks a lot for your help,
> > > >
> > > > Sébastien
> > > >
> > > >
> > > > _______________________________________________
> > > > Getfem-users mailing list
> > > > address@hidden
> > > > https://mail.gna.org/listinfo/getfem-users
> 
> 
>